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| author | Will Newton <will.newton@linaro.org> | 2014-03-12 16:14:51 +0000 |
|---|---|---|
| committer | Will Newton <will.newton@linaro.org> | 2014-04-17 11:38:50 +0100 |
| commit | 37d350073888887637aa67dddf988d9c4b226032 (patch) | |
| tree | a893453561890056eca3e79e58e0564b15b8b10d /ChangeLog | |
| parent | 423a7160af7fcffc61aac5e2e36d0b6b5b083214 (diff) | |
| download | glibc-37d350073888887637aa67dddf988d9c4b226032.tar.gz glibc-37d350073888887637aa67dddf988d9c4b226032.tar.xz glibc-37d350073888887637aa67dddf988d9c4b226032.zip | |
aarch64: Re-implement setcontext without rt_sigreturn syscall
The current implementation of setcontext uses rt_sigreturn to restore the contents of registers. This contrasts with the way most other architectures implement setcontext: powerpc64, mips, tile: Call rt_sigreturn if context was created by a call to a signal handler, otherwise restore in user code. powerpc32: Call swapcontext system call and don't call sigreturn or rt_sigreturn. x86_64, sparc, hppa, sh, ia64, m68k, s390, arm: Only support restoring "synchronous" contexts, that is contexts created by getcontext, and restoring in user code and don't call sigreturn or rt_sigreturn. alpha: Call sigreturn (but not rt_sigreturn) in all cases to do the restore. The text of the setcontext manpage suggests that the requirement to be able to restore a signal handler created context has been dropped from SUSv2: If the context was obtained by a call to a signal handler, then old standard text says that "program execution continues with the program instruction following the instruction interrupted by the signal". However, this sentence was removed in SUSv2, and the present verdict is "the result is unspecified". Implementing setcontext by calling rt_sigreturn unconditionally causes problems when used with sigaltstack as in BZ #16629. On this basis it seems that aarch64 is broken and that new ports should only support restoring contexts created with getcontext and do not need to call rt_sigreturn at all. This patch re-implements the aarch64 setcontext function to restore the context in user code in a similar manner to x86_64 and other ports. ChangeLog: 2014-04-17 Will Newton <will.newton@linaro.org> [BZ #16629] * sysdeps/unix/sysv/linux/aarch64/setcontext.S (__setcontext): Re-implement to restore registers in user code and avoid rt_sigreturn system call.
Diffstat (limited to 'ChangeLog')
| -rw-r--r-- | ChangeLog | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog index b8fa520e19..55dcc2b652 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,10 @@ +2014-04-17 Will Newton <will.newton@linaro.org> + + [BZ #16629] + * sysdeps/unix/sysv/linux/aarch64/setcontext.S (__setcontext): + Re-implement to restore registers in user code and avoid + rt_sigreturn system call. + 2014-04-17 Wilco <wdijkstr@arm.com> * sysdeps/arm/math-tests.h: New file: Set ARM math-test settings. |